#include <stdio.h>
int main() {
    /* code */
    int num;
    printf("请输入一个正整数：");
    scanf("%d", &num);
    char str[20];
    sprintf(str, "%d", num);
    for (int i = sizeof(str) - 1; i > -1; i--) {
        printf("%c", str[i]);
    }
    return 0;
}
